Update element last offset in all scenes

This CL fixes a bug that was caused by ag/25641284: even if a shared
element does not need to be placed/drawn in a scene, we should still
compute and update its lastOffset in that scene.

Bug: 308961608
Test: ElementTest
Flag: N/A
Change-Id: Ibe691a53e220ccf4ad64402f460c473a1d595d1d